This invention relates to a paper feeder for use with a laser printer. More particularly, this invention relates to high capacity paper feeder that can be adapted for use with a wide variety of laser printers of different makes and models and provide a feeding capacity in excess of fifteen hundred sheets of printing paper.
Due to the proliferation of personal computers, laser printers have become one of the most popular equipment in today's office environment. One of the main advantages of laser printers is their ability to provide very high quality printing in a minimal amount of time. Although laser printers have seen significant improvements most notably in the areas of built-in fonts and printing speed, most of the paper feeders, which are in the form of paper trays, remain largely unchanged form those used in the early models and provide only relatively limited feeding capacity. The increase in printing speed results in an increased frequency at which the paper tray must be replenished. Furthermore, in order to save capital cost and office space, several computers are often connected to the same laser printer and share the printing load therewith. This further increases the frequency at which the paper tray must be refilled.
Unlike dot matrix printers, which can receive a continuous roll of paper having perforated edges, a laser printer can be fed only on a sheet-by-sheet basis. Currently, the paper sheets to be fed into the laser printer are stored in a paper tray attached to the feeding port of the laser printer. Due to the weight exerted by the paper sheets, the capacity of a paper tray can not be significantly increased over the current capacity. Most of the commercially available laser printer paper trays have a capacity of approximately two hundred (200) sheets of paper. For a new model laser printer, the speed of printing can be more than eleven (11) sheets per minute, as opposed to four (4) sheets per minute for the older models. This means that the paper tray will be emptied every twenty minutes when the laser printer is operating at full speed. To avoid office interruptions due to the laser printer running out of paper, the paper tray must be frequently inspected and refilled to make sure that it has enough paper to satisfy the printing need. Such a limitation is very inconvenient to laser printer users and has become one of the main bottlenecks in today's high-tech office environment.
Another problem arises when attempting to develop an "add-on" sheet feeder for laser printers. Different makes and models of laser printers that using same printer engine are often manufactured having sheet feedings port at similar height. For example, the laser printers that using Canon SX printer engine have approximately the same height for its sheet feeding port such as the following laser printers: Hewlett Packard laser Jet III and IIID, Laser Jet II, and IID, Apple Laser Writer Series II, Canon LBP-8 II, III, Brother HL-8 and HL-8E, Wang LDP8, and QMS PS810, PS820, and PS825, to name a few. However, although most of the sheet feeding ports are similar in height, there is still a range of difference of approximately 15 mm among various laser printers. This difference in height could cause difficulties in attempts to provide a sheet feeder that is to be universally adaptable for use with laser printers of different brand.